自由基促进性Mn-Mo-W/CNT协同脱除富氧燃烧烟气Hg/NO机理研究

Although NO could be efficiently reduced through the SCR system, N2 formed in the process of oxy-coal combustion power plant would be brought into the high temperature furnace by the circulating flue gas, and the NOx was reformed. To solve this problem, a plan of low temperature SCR system was introduced in this project, and a type of low temperature SCR catalyst was developed. Hg and NO could be simultaneous removed by this catalyst. Based on the high efficiency of Hg/NO removal by Mn-Mo/CNT at low temperature in O2/N2 combustion atmosphere, and the characteristics that the formation of CO/OH radicals from CO2 and H2O could be promoted by oxygen vacancies on the surface of WO3 nanotube, the Mn-Mo-W/CNT catalyst was constructed. The formation mechanism of free radicals on the surface of Mn-Mo-W/CNT was revealed by isotope tracing and NMR spectroscopy analysis. The formation of oxygen vacancies and free radicals on the surface of Mn-Mo-W/CNT was strengthened. The fast electron transfer mechanism mediated by electronic shuttle in catalyst was elucidated. Determining the reaction path of Hg/NO removal on the catalyst surface of Mn-Mo-W/CNT. The catalyst for Hg/NO efficiently removal in oxy-coal combustion flue gas (high concentration of CO2 and H2O) was deeply developed. Combined quantum chemistry and chemical kinetics calculation, the mechanism model of Hg/NO synergistic removal by Mn-Mo-W/CNT in oxy-coal combustion flue gas was established, which laid a foundation for the development of low temperature SCR catalyst for oxy-coal combustion flue gas.

高温SCR系统虽可高效还原NO，但富氧燃烧电厂SCR过程生成的N2又会被循环烟气带入高温炉膛，并再次形成NO。针对这一难题，本项目提出SCR系统低温布置方式，并制备出低温SCR催化剂，实现富氧燃烧烟气Hg/NO协同脱除。拟基于空气燃烧中Mn-Mo/CNT低温高效Hg/NO脱除性能，利用WO3纳米管表面氧空位可促使CO2和H2O形成CO/OH自由基的特点，强化催化剂表面氧空位、自由基形成，构建Mn-Mo-W/CNT催化剂。通过同位素示踪与核磁共振波谱分析等技术，揭示自由基在催化剂表面形成机理，阐明电子穿梭体介导在催化剂中的电子快速转移机制，掌握Hg/NO在催化剂表面反应途径，开发出适于富氧燃烧烟气（高浓度CO2和H2O）高效脱除Hg/NO的催化剂。结合量子化学和化学动力学计算，建立Mn-Mo-W/CNT协同脱除富氧燃烧烟气Hg/NO机理模型，为富氧燃烧烟气低温SCR催化剂开发奠定基础。

富氧燃烧烟气中的单质汞因会对CO2压缩设备造成危害而必须脱除，且富氧燃烧电厂烟气高温SCR系统虽可高效还原NO，但催化还原反应生成的N2又会被循环烟气带入高温炉膛，并再次形成NO。基于该难点，本项目开发了适于在低温高硫环境中催化氧化单质汞的锰负载型碳纳米管催化剂和锰纳米管催化剂。获得了锰负载型碳纳米管催化剂的脱汞性能，在复杂模拟烟气中，添加6% WO3的锰负载型碳纳米管催化剂在100℃时的脱汞效率可以达到98%。通过不同烟气组分对该催化剂催化氧化单质汞的影响，揭示了W在锰负载型碳纳米管催化剂催化氧化单质汞的作用机理，构建了锰负载型碳纳米管催化剂催化氧化单质汞的动力学模型。为进一步提升催化剂中锰的催化活性，利用水热法合成了锰纳米管催化剂，并针对性进行了抗硫改性，在高浓度CO2存在的条件下，该类催化剂催化氧化单质汞的效率可以达到99%。同时，揭示了不同燃煤烟气组分对锰纳米管催化剂催化氧化单质汞的影响机制，阐明了改性锰纳米管催化剂的抗硫机理，为低温高硫环境中SCR催化剂的开发奠定了理论基础。项目团队共发表标注项目号（51906182）的SCI论文7篇，其中项目负责人以第一或通讯作者在Fuel、ChemistrySelect等发表SCI论文6篇。申请发明专利1件。参加工程热物理年会3人次，其中作口头报告1次。培养博士研究生1名，硕士研究生3名。